Networked attached storage (NAS), often refers to a computing system, attached to a network, which provides file-based data storage services to other devices on the network. A NAS system, or NAS device, may include a file system (e.g., under Microsoft Windows) that manages the data storage services, but is generally controlled by other resources via an IP address or other communication protocol. A NAS device may also include an operating system, although the operating system is often configured only to facilitate operations performed by the NAS system. Mainly, a NAS device includes one or more redundantly arranged hard disks, such as RAID arrays. A NAS device works with various file-based and/or communication protocols, such as NFS (Network File System) for UNIX or LINUX systems, SMB/CIFS (Server Message Block/Common Internet File System) for Windows systems, or iSCSI (Internet SCSI) for IP communications.
NAS devices provide a few similar functionalities to Storage Area Networks (SANs), although typical NAS devices only facilitate file level storage. Some hybrid systems exist, which provide both NAS and SAN functionalities. However, in these hybrid systems, such as Openfiler on LINUX, the NAS device serves the SAN device at the file level, and not at a file system level, such as at the individual file level. For example, the assignee's U.S. Pat. No. 7,546,324, entitled Systems and Methods for Performing Storage Operations Using Network Attached Storage, describes how individual files in a NAS device can be written to secondary storage, and are replaced in the NAS device with a stub having a pointer to the secondary storage location where the file now resides.
A NAS device may provide centralized storage to client computers on a network, but may also assist in load balancing and fault tolerance for resources such as email and/or web server systems. Additionally, NAS devices are generally smaller and easy to install to a network.
NAS device performance generally depends on traffic and the speed of the traffic on the attached network, as well as the capacity of a cache memory on the NAS device. Because a NAS device supports multiple protocols and contains reduced processing and operating systems, its performance may suffer when many users or many operations attempt to utilize the NAS device. The contained hardware intrinsically limits a typical NAS device, because it is self-contained and self-supported. For example, the capacity of its local memory may limit a typical NAS device's ability to provide data storage to a network, among other problems.
The need exists for a system that overcomes the above problems, as well as one that provides additional benefits. Overall, the examples herein of some prior or related systems and their associated limitations are intended to be illustrative and not exclusive. Other limitations of existing or prior systems will become apparent to those of skill in the art upon reading the following Detailed Description.